Charles d



(No Model.)

0. D. JENNEY.

DYNAMO ELECTRIC MACHINE. No. 424.065. Patented Mar. 25, 1890.

n ruins, Mo-UIMIHM Wnhington. n.c.

A UNITED STATES PATENT OFFICE.-

CHARLES D. JENNEY, OF INDIANAPOLIS, INDIANA.

DYNAMO-ELECTRIC MACH l N E.

SPECIFICATIbN forming part of Letters Patent No. 424,065, dated March25, 1890.

Application filed April 16, 1889. Serial No. 307,431. (No model.)

To all whom it may concern:

Be it known that I, OHARLEs D. J ENNEY,a citizen of the United States,residing at In dianapolis, in the county of Marion and State of Indiana,have invented certain new and useful Improvements in Dynamo-ElectricMachines,of which the following is a specification.

The object of my said invention is to provide an improved constructionof dynamoelectric machine, by which construction much of the laborusually employed to secure a perfect magnetic union between the core ofthe field-magnet and the pole-pieces is saved, the efficiency of themachine is increased, its construction simplified, and its costmaterially lessened, as will be hereinafter more fully described andclaimed.

Referring to the accompanying drawings, which are made a part hereof,and on which similar letters of reference indicate similar parts, Figure1 is a perspective View of a dynamo-electric machine embodying my saidinvention, and Fig. 2 a horizontal section through a portion thereof onthe dotted line 2 2.

In said drawings, the portion marked AA represent the two pole-pieces ofthe dynamo, B the core of the field-magnet, and C the armature. Thepole-pieces A and A are of cast-iron and are formed curved from thepoint of contact with the magnet-core outward and toward the armature,the line of curvature being that which practical experiment has provento be the natural curve of the principal lines of magnetic force intheir circuit from end to end of a straight magnet. Thus the leastpossible resistance to said force is provided and any leakage thereof ispracti- Cally-obviated, it being given its own natural direction inwhich to travel through the magnetic circuit, and a greater power issecured. At the rear sides these field-pieces are cast with holes forthe ends of the magnet-core, which holes are bored out to a diameter substantially the same as or slightly less than the diameter of said core.At the rear side slots at are formed and bolt-holes extend throughbosses cast thereon transversely of the slots. In these bolt-holes heavybolts A are inserted, by which, when desired, said pole-pieces can befirmly clamped upon said magnet-core, and a very close and perfectmagnetic union be thus effected. As will be noticed by an examination ofFig. 1, the ends of the polepieces are expanded as they approach thearmature, and thus enable a proportionally longer armature to be used inconnection therewith, while presenting a greater surface thereto.

The core B of the field-magnet is in this machine a large round bar ofwrought-iron. It is carefully turned from each end back a distance equalto the width of the pole-pieces to substantially the size of the holesin said pole-pieces, which are formed to receive them. This usuallyresults in the formation of shallow shoulders on said core, againstwhich the inner faces of the pole-pieces will rest, leaving the centralportion of said core of a somewhat greater diameter than its ends, asindicated by the dotted lines in Fig. 2.

The armature O is of any usual or desired construction, beingillustrated only to show a complete machine and the relative position ofthe parts.

By the usual methods of securing an eflicient magnetic union between themagnet and pole-pieces much expensive labor is required in scraping andrubbing the surfaces, so that they will fit accurately and closelytogether; or when, as is sometimes done, the holes in the pole-piecesare made a trifle smaller than the magnet core and forced thereon byhydraulic or other powerful pressure much expensive machinery is madenecessary, and the construction of such machines has thus been veryexpensive. By means of my invention the surfaces can be turned and boredsufficiently smooth, so that by means of the heavybolts operated bypowerful wrenches they can be forced into such close contact that aperfect union is secured with but comparatively a small amount of laborand without extra machinery, thus saving a great portion of the usualexpense.

In practice after the parts have been finished they are put together byfirst inserting thin wedges in the slots, thus opening the holes in thepole=pieces slightly and permitting the ends of the core to enterwithout any unusual application. of force. After the parts are togetherthe pole-pieces are accurately adjusted in their proper relativepositions, the wedges removed, and the bolts inserted and turned upwith. powerful wrenches, forcing the surfaces Very closely together. Itwill be understood, of course, that in the turning up of the ends of thecore of the field-magnet and the boring of the holes in the pole-piecesto fit over said ends the difference in size between said ends and saidholes is made very slightonlysufficient to make a substantially perfectmagnetic union when the wedges are removed from the slits and the sidesof the pole-pieces clamped onto the ends of the core-for if the holeswere made perceptibly smaller than the ends of the core the variation incurvature thus produced would defeat the-object of the invention.

Having thus fully described my said invention, what I claim as new, anddesire to secure by Letters Patent, is-

1. In a dynamo-electric machine, the combination of the field-magnetcore having its ends turned to fit into holes in the pole-pieces, saidpole-pieces having holes bored therein of a slightly less diameter thanthe ends of said core, with slits extending out from the holes in saidpole-pieces to one side, whereby said holes may be slightly expanded andthe polepieces be permitted to he slipped onto the ends of the core, andbolts by which said polepieces may be clamped tightly onto said corewhen in position, and a firm magnetic union thus eflfected.

2. In a dynamo-electric machine, the combination of a round straightfield-magnet core having its ends turned off to fit into holes in thepole-pieces, said pole-pieces bored out to lit tightly over the ends ofsaid core and divided or slitted at one side of the holes, whereby saidholes are adapted to be expanded slightly, ears on said pole-piecesalongside said slits, bolt-holes in said ears, and bolts passing throughsaid holes, whereby said polepieces maybe clamped tightly on said coreand and a good magnetic union of the parts thus secured without theusual expensive and tedious hand-fitting, substantially as set forth.

3. The combination, in a dynamo-electric machine, of a round straightfield-magnet core, pole-pieces fitted tightly over the ends of said coreand extending out therefrom to one side and expanding in the directionof the axis of the armature and extending in curves from the end of thecore in substantially the natural direction of the principal lines offorce of the field-magnet.

4. The combination, in a dynamoelectric machine, of the field-magnetcore, an armature located to one side of said core, and polepiecessecured to the ends of said core, expanding in the direction of the axisof the armature, and extending from the ends of said core insubstantially the natural direction of the principal lines of force ofthe field-magnet to near said armature, substantially as shown anddescribed.

I11 Witness whereof-I have hereunto set my hand and seal atIndianapolis, Indiana, this 10th day of April, A. D. 1880.

CHARLES D. JENNEY. lVitnesses:

E. W. BRADFORD, O. W. H. BROWN.

